In digital cameras, autofocus may be used to focus on an object of interest. Such digital cameras may be provided as stand alone devices or they may be integrated into a multipurpose device such as a smartphone or the like. In various implementations, digital cameras may use phase based autofocus (or phase autofocus) or contrast based autofocus. Currently, mobile camera devices such as point and shoot cameras and mobile cameras integrated into multipurpose devices such as smartphones tend to use contrast based autofocus, but phase autofocus is becoming more widespread in such mobile camera devices. For example, phase autofocus may be advantageous in some implementations because it is typically faster than contrast based autofocus. For example, phase autofocus may allow a digital camera to determine the correct direction and amount of lens position movement based on a single frame of captured information, which may increase focusing speed. Furthermore, phase autofocus may be advantageous because it limits or eliminates overshoot (e.g., the camera changing lens position past the position of focus to obtain the information needed to determine the position of focus as performed in contrast based autofocus). Such overshoots take time and can reduce quality in video capture.
However, phase autofocus is not reliable for all scenes and in all conditions. Such problems may be particularly pronounced in small sized digital cameras, cameras integrated into smartphones, and mass produced digital cameras.